The present invention relates generally to the field of data communications for personal computers (PCs), and in particular to a system for enhancing data access over a communications link.
The Internet is quickly becoming the preferred data communications medium for a broad class of computer users ranging from private individuals to large multi-national corporations. Such users now routinely employ the Internet to access information, distribute information, correspond electronically, and even conduct personal conferencing. Indeed, an ever-growing number of individuals, organizations and businesses have established a presence on the Internet through "web pages" on the World-Wide Web (WWW).
At the same time that the Internet's popularity has been growing, the trend in personal computer design has been towards increased portability. This trend is best evidenced by the rapid growth in popularity of so-called "notebook" or "laptop" computers. Unfortunately, while PCs are becoming both more powerful and more portable, advances in communications infrastructure have not kept pace.
A primary limitation on the ability of personal computers to exploit the Internet to full benefit is a lack of sufficient communications bandwidth. Similar problems may be caused by such conditions as high network traffic, even for high-speed Internet access lines. Outside of an office environment, for example, PCs typically connect to the Internet via POTS (Plain Old Telephone Service) or wireless modems at speeds ranging from 9.6 to 14.4 kbps. Such speeds are substantially lower than typical office LAN (Local Area Network) bandwidths. This limited data communications capability translates into very long user-visible latencies when users interact with the Internet using such technologies.
Communications bandwidth limitations also cause problems for users who access the Internet in a variety of ways depending upon where they are physically located. It is quite common for a user to have more than one computer from which he or she accesses the Internet, such as an office PC, a home PC and a mobile PC for travel. Alternatively, a user may employ a single mobile PC to access the Internet from multiple locations, including office, home or remote sites. Such clients may become frustrated by differences in access speeds as they move among these various work environments, as there may be dramatic differences in the time required to access the exact same content given the widely-disparate communications bandwidths available (e.g., 10 Mb over an office LAN v. 9.6 kb over a modem). Such users typically are not tolerant of poor data access times, demanding comparable performance regardless of where and how they happen to be accessing the Internet.
Slow data communications speeds are especially problematic for the mobile and home computer industries, since available content is typically becoming richer in time frames measured in terms of weeks to months, while mobile and home computer bandwidths are typically getting broader in time frames measured in terms of years to decades. In order to remain competitive, it is desirable that mobile and home computers maintain application equivalence with office desktop PCs.
In view of this challenge, the mobile and home computer industries have developed a number of approaches for dealing with the problem of slow data communications. One such method is to use a text-only browser; that is, users are simply unable to download data other than text. While this method certainly reduces user-visible latencies by avoiding richer data types such as images and video, it also diminishes the value of most Web pages and significantly underuses the advanced media capabilities of PCs. The end result is decreased user satisfaction.
Another approach is for content providers to create content in low-quality, non-rich formats. Such content may be represented using substantially less data than high-quality, rich formats, thus shortening the time required for transmission to a user. This method, however, presents a user site with the Hobson's choice of decreased content quality for all of its users (including those with access to high-bandwidth connections) or intolerable access speeds for users with low-bandwidth connections. Since Web sites must compete with other media industries, such as television, for the attention of users, today most sites are choosing high-quality, rich content. The result is that low-bandwidth connections are becoming increasingly undesirable, resulting in many rich content Web sites creating and maintaining multiple versions of objects offering varying degrees of resolution from which the user must choose.
Yet another approach is data compression. Traditional data compression techniques involve compressing data at the network or packet level. Examples include modem compression (such as V.42) and PPP/IP header compression. Such techniques are by necessity non-lossy because they lack information about the data being compressed. Compression rates are generally no more than 2.times. end-to-end for all compression algorithms combined, being limited by the fact that compressing already-compressed data is largely ineffective. This is especially true for the media datatypes often used on the Web, such as video, audio and image. Content containing these rich datatypes are usually stored in compressed format already, meaning traditional compression techniques achieve substantially less than the 2.times. compression rate.
None of the foregoing approaches provide a satisfactory solution to the problem of providing users with fast access to the rich content available over computer networks such as the Internet.